The problem of derailments in the field of rail transport is, unfortunately, quite frequent, resulting in numerous losses due to the damage caused to the vehicles and tracks and the loss of revenue proportional to the time that elapses until the affected tracks are once again operational and open to traffic.
These serious consequences resulting from the derailment of railway vehicles have made necessary the use of equipment that can quickly detect the derailment of the vehicles with a sufficient degree of reliability and immediately apply the appropriate measures.
To date, these measures have consisted of applying the emergency brake as soon as the derailment was detected, braking the train as quickly as possible and stopping it in order to minimize any effect a derailment might have on persons, goods, vehicles and infrastructures.
Specifically, systems based on an inertia sensor are known in which the sensor is triggered when the derailment is detected, quickly emptying the automatic brake pipe (ABP) and causing the train's emergency brake to be applied, which acts on all the cars, including the one(s) that derailed.
However, these systems have a major drawback, which is the fact that when the brake is applied on all of the vehicles in the train as a result of the derailment of one or several of them, the wheels of all these vehicles remain braked, including those of the derailed ones. This prevents them from rolling, with the disadvantage that when the derailed vehicles move over the ballast and sleepers the wheels can become locked, with dire results, as this may cause other vehicles to derail or even tip over.
Moreover, on certain occasions when a derailment takes place and thus the ABP is opened, the driver or engineman does not notice this until some time afterwards. This can particularly occur on very long trains, which in some cases might be over two kilometers in length, as the drop in pressure in the ABP takes place gradually down the length of the train, starting with the vehicles nearest the derailed one and continuing along the entire pipe. Thus, if the vehicle that derails is at the end of the train, the drop in pressure in the ABP will not take effect in the first vehicles until a certain amount of time has elapsed, during which the train will continue travelling because this circumstance will not have been noticed in the control station, either.
Therefore, this means that the brake is not applied at the same time in all of the vehicles in the train, which results in irregular braking and a more prolonged braking time.